Cranial Repair Implant Molding Device

ABSTRACT

A cranial implant molding device having a frame or base that receives a bottom or convex molding plate and a top or concave molding plate in a manner whereby the two plates are separated a distance to receive a settable or curable implant forming material therebetween. The plates are separated by a compressible member such that by the use of threaded mechanical fasteners or similar members the distance between the two plates can be adjusted by tightening or loosening the mechanical members. The thickness of the implant is varied by varying the separation distance on different sides of the frame.

This application is a divisional application of U.S. patent applicationSer. No. 13/437,098, now U.S. Pat. No. 8,673,014, issued Mar. 18, 2014,claiming the benefit of U.S. Provisional Patent Application Ser. No.61/516,295, filed on Apr. 1, 2011, the disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of artificial implants forbone repair, and more particularly relates to implants that replacedamaged or missing portions of bones, and even more particularly relatesto implants for use in repairing the cranium. The invention relatesgenerally to the field of molding devices for the manufacture of cranialimplants as utilized in cranial repair methodologies.

In many situations it is medically necessary to replace a relativelylarge portion of the cranium that has either been removed by a surgeonfor access to the brain or to address damaged due to disease, accidentor physical attack. Typically a surgeon will be able to remove a portionof the skull in a controlled shape or configuration, such as for examplea circle, triangle or the like. The surgeon then has the option ofreplacing the removed bone material with a pre-formed replacementimplant that approximates the needed the shape.

A problem sometimes arises whereby the assortment of pre-formed implantsdoes not properly accommodate the variations in thickness of the cranialbone. The pre-manufactured cranial implant may be too thick or too thinoverall. The cranial bone may also vary in thickness, such that forexample one side of the removed bone may be thicker than the other side.

It is an object of this invention to provide a cranial implant moldingdevice that is adjustable such that cranial implants of differentoverall thicknesses can be produced. It is a further object to provide acranial implant molding device that is adjustable such that opposingsides of a single implant may be produced having differing thicknesses.

SUMMARY OF THE INVENTION

A method of cranial repair and the device used in the method, thecranial implant molding device comprising a frame or base having abottom or convex mold plate and a top or concave mold plate disposed ina manner whereby the two plates are separated a short distance to createa mold cavity to receive a settable or curable implant forming material.The top mold plate comprises a mold cavity top wall located between apair of lateral top plate flanges and the bottom mold plate comprises amold cavity bottom wall located between a pair of lateral bottom plateflanges. By the use of threaded mechanical fasteners or similar meansthe distance between the two mold plates can be adjusted by tighteningor loosening the mechanical members. Preferably, at least onecompressible member is disposed between each top plate flange and bottomplate flange. The thickness of the implant is varied by adjusting theseparation distance of the flanges to be equal on both sides of the moldcavity to produce an implant with each side being of the same thickness.An implant varying in thickness from one side to the other is producedby setting the separation distance of the flanges on one side of themold cavity different from the separation distance on the other side ofthe mold cavity. The molding device may comprise a plurality of moldplate sets, the sets varying in the amount of curvature, size, shape,etc.

When a surgeon removes a cranial bone portion the thickness andconfiguration of the removed bone portion is measured and the propercombination of top and bottom mold plates are chosen to best match theconfiguration. The separation distance between the mold plates is thenadjusted to best match the thickness of the opposing edges of theremoved bone portion, such that the resulting cranial implant soproduced will require minimal post-curing shaping prior to implantation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an embodiment of the device.

FIG. 2 is a top view of the embodiment of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, the embodiments for the invention willnow be described in detail. In a general sense, the invention is amethod of cranial repair and the cranial implant molding device usedtherein comprising a frame or base that receives a bottom or convex moldplate and a top or concave mold plate in a manner whereby the two platesare separated a short distance to create a mold cavity to receive asettable or curable implant forming material. The top mold platecomprises a mold cavity top wall located between a pair of top plateflanges and the bottom mold plate comprises a mold cavity bottom walllocated between a pair of bottom plate flanges. By the use of threadedmechanical fasteners or similar means the distance between the two moldplates can be adjusted by tightening or loosening the mechanicalmembers. Preferably, at least one compressible member is disposedbetween each top plate flange and bottom plate flange. The thickness ofthe implant is varied by adjusting the separation distance of theflanges to be equal on both sides of the mold cavity to produce animplant with each side being of the same thickness. An implant varyingin thickness from one side to the other is produced by setting theseparation distance of the flanges on one side of the mold cavitydifferent from the separation distance on the other side of the moldcavity. The molding device may comprise a plurality of mold plate sets,the sets varying in the amount of curvature, size, shape, etc.

The invention may be broadly defined as a cranial implant moldingdevice, and its method of use in cranial repair surgery, comprising abottom plate comprising a mold cavity bottom wall, a first and a secondbottom plate flange positioned to either side of said mold cavity bottomwall, and a depending wall connecting each of said bottom plate flangesto said mold cavity bottom wall; a top plate comprising a mold cavitytop wall, a first and a second top plate flange positioned to eitherside of said mold cavity top wall, a depending wall connecting each ofsaid top plate flanges to said mold cavity top wall, and a vent portdisposed in said mold cavity top wall; a base comprising a recess, saidbottom plate and said top plate being positioned on said base such thatsaid mold cavity bottom wall and said mold cavity top wall are disposedwithin said recess and such that said mold cavity bottom wall isseparated from said mold cavity top wall to form a mold cavity adaptedto receive implant forming material; at least one mechanical adjustmentmember extending through said first top plate flange and said firstbottom plate flange and into said base, and at least one othermechanical adjustment member extending through said second top plateflange and said second bottom plate flange and into said base, wherebymanipulation of said mechanical adjustment members adjusts the distancebetween said first top plate flange and said first bottom plate flangeand between said second top plate flange and said second bottom plateflange, thereby adjusting the distance between said mold cavity top walland said mold cavity bottom wall.

The invention may be further defined as such a device wherein saidmechanical adjustment members may be independently manipulated, suchthat the distance between said first top plate flange and said firstbottom plate flange may be different from the distance between saidsecond top plate flange and said second bottom plate flange, and furthercomprising at least one compressible resilient member disposed betweensaid first top plate flange and said first bottom plate flange, and atleast one resilient member disposed between said second top plate flangeand said second bottom plate flange, and further wherein said moldcavity bottom wall is generally convex and said mold cavity top wall isgenerally concave, and further wherein said top plate nests within saidbottom plate, and further wherein said recess is four-sided, and furthercomprising a plurality of said top mold plates and a plurality of saidbottom mold plates, wherein said mold cavity top wall of each said topmold plate is different in curvature, configuration or shape and whereinsaid mold cavity bottom wall of each said bottom mold plate is differentin curvature, configuration or shape.

The methodology comprises the steps of removing a portion of cranialbone that requires replacement to create a defined cranial opening inthe cranium. The measurements of the removed cranial bone or of theremaining cranial edges are then taken to determine the necessary size,configuration, curvature and thickness of the implant to approximate thedefined opening. The proper bottom and top mold plates 12 and 13 arechosen to best match the dimensions of the cranial opening, and the topmold plate 13 is adjusted relative to the bottom mold plate 12 to bestmatch the edge thickness or thicknesses of the removed portion. Theimplant is then prepared and cured, removed from the mold, and furthershaped or processed as required to optimize the replacement match. Theimplant is then positioned in the cranial opening and secured to thecranium using known methodologies, such as with adhesives, other bondingmaterials or mechanical fasteners.

With reference now to the drawings, the cranial implant molding device10 comprises a base or frame member 11 having a central recess 19,preferably four-sided, to receive a paired set of mold plates 12 and 13.The base 11 receives and retains a bottom mold plate 12 and a top moldplate 13 in separated manner such that in combination the two plates 12and 13 define a generally centralized mold cavity 20 to receive animplant forming material. The bottom mold plate 12 comprises a moldcavity bottom wall 23, the mold cavity bottom wall 23 being generallyconvex on the side facing the mold cavity 20 and top mold plate 13. Thebottom mold plate 12 further comprises first and second flanges 14positioned on opposing sides of the mold cavity bottom wall 23, thebottom plate flanges 14 joined to the mold cavity bottom wall 23 bydepending walls 25. In a basic embodiment the bottom mold plate 12 maybe permanently affixed to the base 11. The top mold plate 13 comprises amold cavity top wall 22, the mold cavity top wall 22 being generallyconcave on the side facing the mold cavity 20 and bottom mold plate 12,with the mold cavity top wall 22 provided with a venting port 18. Thetop mold plate 13 further comprises first and second flanges 15positioned on opposing sides of the mold cavity top wall 23, the topplate flanges 15 joined to the mold cavity top wall 22 by dependingwalls 24. The mold cavity top wall 22 and mold cavity bottom wall 23 arepositioned below the height of the flanges 14 and 15, and the top wallflange 15 will extend inwardly slightly farther than the bottom wallflange 14, such that the top plate depending walls 24 are receivedwithin the bottom plate depending walls 25 and the top mold plate 13 isgenerally nested within the bottom mold plate 12.

The molding device 10 is preferably capable of receiving a number ofmold plates 12 and 13 possessing having mold cavity top walls 22 andmold cavity bottom walls 23 of different shapes, curvatures, sizes,etc., such that implants of varying shapes and sizes may be produced.The mold cavity walls 22 and 23 may also be provided with projections ordepressions to create additional surface features in the implant. Thus,the molding device 10 may be a component of a kit that possessesmultiple sets of mold plates 12 and 13.

At least one mechanical adjustment member 17, and possibly multiplemechanical adjustment members 17, is provided on each side of base 11.As shown in the drawings, the mechanical adjustment members may comprisethreaded bolts received within threaded bores 21, where the threadedportions extend through apertures disposed in the first flanges 14 and15 and the second flanges 14 and 15. The top plate flanges 15 may besecured to upper portion of the mechanical adjustment members 17 suchthat rotation of the mechanical adjustment members 17 raises or lowersthe top plate 13 relative to the bottom plate 12. Alternatively, the topplate flanges 15 may not be directly connected to the mechanicaladjustment members 16, in which case the implant forming materialdisposed in the mold cavity 20 serves to provide upward pressure againstthe top plate 13.

Most preferably, one or more compressible, resilient members 16, such asfor example circular washers, rectangular pads, springs or similarmembers, are positioned between the first flanges 14 and 15 and betweenthe second flanges 14 and 15. With this structure the compressibleresilient members 16 provide upward pressure against the top plateflanges 15 such that the top plate flanges 15 do not require connectionto the mechanical adjustment members 17. Manipulation of the mechanicaladjustment members 17 to vary the separation distance of the top plate13 from the bottom plate 12 results in compression or expansion of thecompressible resilient members.

To create an implant, the appropriate bottom and top mold plates 12 and13 that most closely approximate the desired curvature, shape andlateral dimensions of the removed cranial bone segment are selected andthe bottom mold plate 12 is positioned on the base 11. Implant formingmaterial, such as a liquid, putty or cement of any type suitable for theformation of biocompatible implants, is then placed, poured, injected,sprayed or otherwise deposited onto the bottom mold plate 12. Thecompressible resilient members 16, if utilized, are then properlypositioned on the bottom plate flanges 14 and the top mold plate 13 isplaced onto the base 11. The mechanical adjustment members 17 areinserted through the flanges 14 and 15 and the compressible resilientmembers 16 and into the bores 21 in base 11. The mechanical adjustmentmembers 17 are then manipulated to press the top plate 13 toward thebottom plate 12 to compress and distribute the implant forming materialwithin the mold cavity 20, excess implant forming material being able toescape through the venting port 18 and be retained within the baserecess 19. The top plate 13 is lowered to the desired separationdistance relative to the bottom plate 12, equal on both sides to producean implant having equal edge dimensions and varying to produce animplant having opposing edges of different thicknesses. Once the implantforming material has sufficiently cured, the top plate 13 is removed andthe implant is released from the bottom plate 12.

In an alternative method for creating a cranial implant, the appropriatebottom and top mold plates 12 and 13 that most closely approximate thedesired curvature, shape and lateral dimensions of the removed cranialbone segment are selected and positioned on the base 11, and themechanical adjustment members 17 are inserted through flanges 15, thecompressible resilient members 16 and flanges 14 and into the bores 21.Where the edge thicknesses of the cranial implant are to be equal onboth sides, the separation distance between the first flanges 14 and 15and between the second flanges 14 and 15 are set to the desired equaldistance. Where one side of the implant is to be thinner than the other,the separation distance of the set of first flanges 14 and 15 on oneside of the mold cavity 20 is set to one dimension and the set of secondflanges 14 and 15 on the other side of the mold cavity 20 is set to adifferent dimension. Implant forming material is then injected,extruded, poured or otherwise introduced through vent port 18 into themold cavity 20 defined by the two mold plates 12 and 13. The ventingport 18 also serves to release volatiles or any excess or expandingimplant forming material, which is retained within the base recess 19.Any properly biocompatible implant forming material may be used, such asa putty or cement previously approved for medical purposes, that uponcuring or hardening produces a substantially rigid, structurally strongimplant. For example, and not meaning to be limiting in any way, a bonecement marketed under the brand name KRYPTONITE by Doctor's ResearchGroup, Inc., has been shown to be suitable for this purpose. Once theimplant has cured, the top mold plate 13 is removed and the implant isavailable for further processing if needed prior to implantation.

It is understood that equivalents and substitutions to certain elementsand structures set forth above may be obvious to those of ordinary skillin the art, and the embodiments and examples as described are not meantto be limiting. Therefore the true scope and definition of the inventionis to be as set forth in the following claims.

We claim:
 1. A cranial implant molding device comprising: a bottom platecomprising a mold cavity bottom wall, a first and a second bottom plateflange positioned to either side of said mold cavity bottom wall, and adepending wall connecting each of said bottom plate flanges to said moldcavity bottom wall; a top plate comprising a mold cavity top wall, afirst and a second top plate flange positioned to either side of saidmold cavity top wall, a depending wall connecting each of said top plateflanges to said mold cavity top wall, and a vent port disposed in saidmold cavity top wall; a base comprising a recess, said bottom plate andsaid top plate being positioned on said base such that said mold cavitybottom wall and said mold cavity top wall are disposed within saidrecess and such that said mold cavity bottom wall is separated from saidmold cavity top wall to form a mold cavity adapted to receive implantforming material; at least one mechanical adjustment member extendingthrough said first top plate flange and said first bottom plate flangeand into said base, and at least one other mechanical adjustment memberextending through said second top plate flange and said second bottomplate flange and into said base, whereby manipulation of said mechanicaladjustment members adjusts the distance between said first top plateflange and said first bottom plate flange and between said second topplate flange and said second bottom plate flange, thereby adjusting thedistance between said mold cavity top wall and said mold cavity bottomwall.
 2. The device of claim 1, wherein said mechanical adjustmentmembers may be independently manipulated, such that the distance betweensaid first top plate flange and said first bottom plate flange may bedifferent from the distance between said second top plate flange andsaid second bottom plate flange.
 3. The device of claim 1, furthercomprising at least one compressible resilient member disposed betweensaid first top plate flange and said first bottom plate flange, and atleast one resilient member disposed between said second top plate flangeand said second bottom plate flange.
 4. The device of claim 1, whereinsaid mold cavity bottom wall is generally convex and said mold cavitytop wall is generally concave.
 5. The device of claim 1, wherein saidtop plate nests within said bottom plate.
 6. The device of claim 1,wherein said recess is four-sided such that said recess retains excessimplant forming material therein.
 7. The device of claim 1, furthercomprising a plurality of said top mold plates and a plurality of saidbottom mold plates, wherein the configuration of said mold cavity topwall of each said top mold plate is different and wherein theconfiguration of said mold cavity bottom wall of each said bottom moldplate is different.
 8. A cranial implant molding device comprising: abottom plate comprising a generally convex mold cavity bottom wall, afirst and a second bottom plate flange positioned to either side of saidmold cavity bottom wall, and a depending wall connecting each of saidbottom plate flanges to said mold cavity bottom wall; a top platecomprising a generally concave mold cavity top wall, a first and asecond top plate flange positioned to either side of said mold cavitytop wall, a depending wall connecting each of said top plate flanges tosaid mold cavity top wall, and a vent port disposed in said mold cavitytop wall; a base comprising a recess, said bottom plate and said topplate being positioned on said base such that said mold cavity bottomwall and said mold cavity top wall are disposed within said recess andsuch that said mold cavity bottom wall is separated from said moldcavity top wall to form a mold cavity adapted to receive implant formingmaterial; at least one compressible resilient member disposed betweensaid first top plate flange and said first bottom plate flange, and atleast one resilient member disposed between said second top plate flangeand said second bottom plate flange; at least one mechanical adjustmentmember extending through said first top plate flange and said firstbottom plate flange and into said base, and at least one othermechanical adjustment member extending through said second top plateflange and said second bottom plate flange and into said base, wherebymanipulation of said mechanical adjustment members adjusts the distancebetween said first top plate flange and said first bottom plate flangeand between said second top plate flange and said second bottom plateflange, thereby adjusting the distance between said mold cavity top walland said mold cavity bottom wall; wherein said mechanical adjustmentmembers may be independently manipulated, such that the distance betweensaid first top plate flange and said first bottom plate flange may bedifferent from the distance between said second top plate flange andsaid second bottom plate flange.
 9. The device of claim 8, furthercomprising a plurality of said top mold plates and a plurality of saidbottom mold plates, wherein the configuration of said mold cavity topwall of each said top mold plate is different and wherein theconfiguration of said mold cavity bottom wall of each said bottom moldplate is different.
 10. The device of claim 8, wherein said top platedepending walls are received within said bottom plate depending walls.11. The device of claim 8, wherein said recess is four-sided such thatsaid recess retains excess implant forming material therein.